Perpendicular drives debut

San Jose, Calif. - Perpendicular recording, a technology that has been in the lab nearly 20 years, has come to light in 2.5-inch disk drives. Hitachi Global Storage Technologies Inc. said it has had a handful of notebooks in the field since December with 2.5-inch drives that use perpendicular recording.

The drives are 100-Gbyte, dual-platter devices with media rotating at 4,200 rpm, the company said. Separately, the world's fourth largest drive maker recently showed a demonstration system hitting a record 230 Gbits/square inch. "No one has shown this kind of areal density," said John Best, chief technology officer of Hitachi GST. "We are at the cusp of the most significant hard-drive technology transition of the past decade," said chief executive officer Jun Naruse.

Best said that Hitachi uses conventional current-in-plane giant magnetoresistive heads with single-pole write heads optimized for the perpendicular media. The disks use a fairly widely agreed-upon thin-film sputtering process.

Hitachi's move was among the first of many expected as drive makers start the transition to the perpendicular recording technology. Seagate Technology Inc., for example, is expected to launch a perpendicular product by year's end.

To keep areal density growing, drive makers believe they must shift from storing magnetic charges longitudinally on a disk's surface to storing them vertically. While it's difficult to push horizontal charges close together, vertical charges will naturally couple, opening the door to smaller recording tracks or more bits stored per track area. But areal density is no longer the sole concern. The rise of consumer electronics demands that drive makers tailor devices for the specific size, power and cost requirements of emerging markets, such as digital video recorders and cell phones.

Nevertheless, perpendicular recording is expected to help vertically integrated companies such as Hitachi GST and Seagate Technology distance themselves, at least temporarily, from their competition.

"Hitachi announced one thing that no one else has: There are laptops being used with working drives. I haven't heard that from anyone else," said John Buttress, research manager for hard drives at International Data Corp. (Framingham, Mass.). The fact that Hitachi is using 2.5-inch notebook drives as its vehicle for the new technology makes sense, he said. The company has its strength in this sector and can define a relatively low-volume, high-margin product that offers relatively low risk and high return on investment.

In response to Hitachi's move, Seagate's chief technology officer, Mark Kryder, said the world's biggest drive maker will also roll out its first devices using perpendicular recording before the end of the year. "We see nothing in this [Hitachi] announcement which is particularly surprising," Kryder said. "We announced areal density of 170 Gbits/square inch in 2003. Hitachi's 230 Gbits/square inch is a small increment over that, and not particularly astonishing." Kryder declined to specify details of Seagate's perpendicular product. IDC's Buttress said he expects it will be similar to Hitachi's, targeting a low-volume, high-margin product line in a sector where Seagate has shown leadership-probably 3.5-inch server drives.

Drive makers generally agree that perpendicular recording will hit in the second half, with products that could sport up to 160 Gbytes/platter. "Perpendicular recording will be an opportunity to put some space between us and the competition, though different companies will use it in different spaces at different times," said Kryder. "Companies that are vertically integrated, like Seagate and Hitachi, are in a better position than those that are not.

Toshiba Corp. was actually the first to disclose plans for perpendicular recording. Several months ago the company said it would ship by September 40- and 80-Gbyte single- and dual-platter versions of its 1.8-inch drives using the technology. Toshiba is presumably being pushed by its major customer, Apple Computer Inc., which uses the drives in its full-size iPod models.

Fujitsu Ltd. could be next. According to IDC's Buttress, its server and notebook lines compete well in performance and Fujitsu has strong R&D in drives. In addition, Fujitsu has a joint venture with TDK and continues to fund an internal head-design group. Western Digital and Maxtor, the world's second and third largest drive makers by units, are also reported to have well-advanced programs on perpendicular recording, Buttress said.

For cost and time-to-market reasons, drive makers are generally expected to introduce perpendicular recording using recording heads that are as similar as possible to those in today's longitudinal drives. A follow-on generation will use current-perpendicular-to-plane (CPP) heads to gain further advantages in areal density. In addition, drive makers are looking at shifting from giant magnetoresistive to tunneling magnetoresistive (TMR) heads to lower signal-to-noise ratios. The varying head types "are independent of the move to perpendicular recording. They're really techniques to scale the heads and make them smaller," said Hitachi's Best.

Though some companies are shipping TMR heads for longitudinal recording today, it is not clear how much they improve SNR, and the transition may be slow, Best said. Meanwhile, materials issues will hamper the move to CPP heads, which are more than a year away, he added.

Buttress said Seagate may use TMR heads to extend the life of its longitudinal drives, mitigating the risks of a fast transition to perpendicular recording in many product families.

Indeed, "We have done a lot of work in TMR and CPP heads. All these technologies help areal density," Kryder said. "Perpendicular technology looks very good, but it probably does not have as many generations as we thought a few years ago. It will be difficult for perpendicular to get to a terabit/square inch, just as it would be a challenge to get longitudinal recording to 200 Gbits/square inch."

Drive makers are divided about what lies beyond what Kryder called "a few years" of perpendicular drives.

"Heat-assisted recording looks very promising to us. We have a small, lower-level program in patterned media, but our view is that heat-assisted technology will be needed sooner rather than later," Kryder said. "Our current guess is that patterned media could be in drives before heat-assisted recording, but it could still go the other way around," said Hitachi's Best. "That technology will lead far beyond densities of 1 Tbit/square inch."

Tech for all seasonsAlthough potentially short-lived, perpendicular recording will eventually cover the waterfront from miniature 1-inch consumer drives to mainstream 2.5-inch notebook and desktop drives to mega 3.5-inch drives used in servers and personal video recorders.

Hitachi GST, formed from the merger of Hitachi's and IBM's drive businesses, has announced that it plans to ship a line of 1-inch longitudinal drives late this year that will eventually hit 10 Gbytes. "Subsequent generations are likely to use perpendicular recording to handle video and other content for the cell phone," said Best.

"The question is, when do users want video in a phone? That's when you'll want hard drives in phones, and we are starting to see some of that," Kryder said.